A mouse is a widely-used input device of a computer for controlling the movement of a computer cursor and inputting a command to the computer. Generally, a mouse comprises an optical sensor and plural mouse buttons. The optical sensor is used for generating a cursor displacement signal. The mouse button is used for generating a command, e.g., a command of launching a specified program. FIG. 1 schematically illustrates the structure of a conventional mouse. As shown in FIG. 1, the mouse 9 is placed on a desk surface T. As the mouse 9 is moved on the desk surface T, the location of the cursor on a display screen (not shown) is corresponding moved. A circuit board 91 is disposed within the mouse 9. A button switch 92 and an optical sensor 93 are disposed on the circuit board 91. The optical sensor 93 comprises a light emitter 931 and a light receiver 932. The button switch 92 is disposed under a pressing shell 94 of the mouse. When the pressing shell 94 is pressed down to push the button switch 92, the button switch 92 generates a button signal (not shown). The light emitter 931 emits a light beam 95 from an inner portion of the mouse. When the light beam 95 is irradiated on the desk surface T, the light beam 95 is reflected to the light receiver 932. That is, the optical sensor 93 detects the planar movement of the mouse 9 on the desk surface T and controls the movement of the computer cursor according to the detecting result.
As mentioned above, a physical pressing action is necessary for the button switch of the conventional mouse to generate the button signal. Moreover, the mouse needs to be operated on a desk surface or a flat surface. If the mouse is placed in the air, the movement of the mouse cannot be judged because the light beam cannot be reflected to the mouse by the desk surface. Moreover, the conventional mouse is only able to sense the planar displacement along the X-Y axial direction, but unable to sense the vertical displacement along the Z axial direction.
In other words, the conventional mouse needs to be further improved.